The aerial pesticide spraying program over Dallas County appears to have reduced the number of mosquitoes that can carry the West Nile virus, at least according to preliminary findings detailed for the Dallas City Council on Monday.

Prior to the spraying, four of five mosquito traps set out by a city contractor collected mosquitoes carrying West Nile. After spraying, none of the traps had mosquitoes carrying West Nile.

A full report from the federal Centers for Disease Control and Prevention probably will not be complete for at least two months, although the city may get some information from the agency by week’s end.

However, First Assistant City Manager A.C. Gonzalez said the early signs are good.

“The very preliminary results suggest we are making headway, that we have been successful at this point,” he said.

Meanwhile Monday, Dallas County health officials confirmed a 12th West Nile-related death, a woman in her 80s who lived in Irving. According to the county’s news release, the victim was diagnosed with West Nile neuroinvasive disease. County health director Zachary Thompson said the woman had underlying medical conditions.

More than 150 people have been diagnosed with West Nile infections in Dallas, and nearly 300 countywide. Five people in Dallas have died.

The aerial spraying has been welcomed by many who fear the spread of the virus. But it has also stirred fear from those who worry that the mosquito poison can harm people, pets and the environment.

Gonzalez praised City Hall’s work in spreading the word about the dangers of West Nile and the city’s effort to address it.

Code Compliance has put its primary focus on standing water complaints and other code violations that could help mosquitoes breed and further spread West Nile.

The department has set a goal of addressing West Nile complaints within 24 hours. Code officers had a backlog of 700 complaints at the start of the weekend. That was down to 50 on Monday, Gonzalez said.

But no response from City Hall can be as effective as citizens making sure that all standing water they see is dumped.

“We cannot, as a city, handle all the acreage we have throughout the city in terms of standing water. We are imploring people to take as much of this on as they can with their own actions,” Gonzalez said.

Mayor Mike Rawlings called on people to turn off their sprinkler systems. Sprinklers are widely associated with the spread of West Nile because they can create constant pools of standing water that are perfect for mosquito breeding.

“I hope we don’t have sprinklers on out there. We don’t need sprinklers right now. I turned my sprinklers off. We’ve had so much rain. Everybody turn off your sprinklers for a little while. I mean, seriously,” he said.

Also Monday, the Denton City Council voted 4-1 to opt out of countywide aerial spraying for adult mosquitoes, after discussing the issue for about two hours. About 20 residents attended the meeting early Monday to voice their opposition to aerial spraying.

County Judge Mary Horn signed an emergency order last week, calling for aerial spraying countywide and giving cities the option to opt out. She expects to announce Tuesday which cities have agreed to spraying, and has said the process could begin as early as Thursday.

Denton County has reported 119 cases of West Nile virus this year, including two deaths.

The Denton County sections of Carrollton, Coppell, Dallas and Plano were included in the Dallas County aerial spraying program that has been completed, Denton County officials said.

The Frisco City Council voted at a special meeting Monday evening not to participate in Denton County’s aerial spraying. The city has had five confirmed human cases of West Nile and has been spraying selected neighborhoods by truck.

Staff reports

Confirmed deaths

Collin County — 1

Dallas County — 12

Denton County — 2

Ellis County — 1

Rockwall County — 0

Tarrant County — 4

TOTAL — 20

SPRAYING

Areas to be sprayed by trucks for mosquitoes:

Lancaster

When: Starting at 10 p.m. Tuesday

Where: All city surface streets

POISON CONTROL

The North Texas Poison Control Center will answer questions about aerial spraying 24 hours a day. Call 1-800-222-1222.